I must confess I'm enjoying thinking of Anakin's Dark Side turn as a sort of "Dr Jekyll/Mr Hyde" concept...but I'm not sure Anakin should be completely unaware of 'Vader's' doings...in other words, it should be a somewhat conscious act.
I don't know how much sympathy we really ought to have for Anakin, especially during the latter stages. Specifically regarding the chilidren, we ought to expect someone being consumed by the Dark Side will commit unpleasant deeds...can we really say, "evil, but no, that's too evil!"? It may seem abrupt, but aren't there many stories of people committing multiple slayings being previously quite normal then "just snapping" ?
Even then, there is a progression...(lemme break in here to say I'm not suggesting it was particularly deftly handled) Anakin's (Vader's?) Tusken massacre was a definite event of Dark Side possession....His confession of "women and children" *should* probably go. George seems to have tried to lessen the apparent severity of this by emphasizing the sand peoples' bestial nature...Cliegg's leg should say it all. Anakin, I think, should at this point be putting up a defense in his mind for having done this thing, till eventually believing the fiction. His ego will be horrified at it, but a thrill at the taste of reckless emotional satisfaction would be underpinned.
Anakin's story ought to be a cautionary tale. We *should* be disturbed at his unnatural teetering between the extremities of his psyche. Those who don't (or aren't allowed to) confront their personal dark side risk being swallowed by it. The Jedi's sole adherence to the Light Side of the Force is just as unnatural as the Sith's to the Dark. The Jedi not allowing Anakin to naturally face his inner demons and darker emotions contributed just as much as Palpatine to his fall. I believe Anakin's first step to bringing balance to the Force was the destruction of the Jedi, and the second the destruction of the Sith, with his son taking a position sublimating the two extremes to an equilibrium. (shit. I think I'm getting too blatantly Jungian here. I'll shut the hell up about it.)
Now, to actually contribute ideas, I think it's just as important to see Sidious' reaction to Anakin's massacre as the Jedi...obviously, he'd be much more pleased (maybe even directing events to an extent...? It could recall Hera's afflicting Herakles with madness resulting in the slaughter of his children...). Additionally, Qui-gon (who seemed to have a more balanced, heretical understanding of the Force) perhaps ought to attempt to contact Anakin directly, maybe towards the end of his fall into darkness, trying desperately to call him back. Or, going with my theory of bringing balance to the Force (a concept I realize many dislike...), would Qui-gon have left things to go to their ultimate progression?
...I sincerely apologize for the preceding incoherent ramble.